Portable Devices: Fuel CellsA Kundu,Queen’s RMC Fuel Cell Research Centre, Kingston, ON, Canada JH Jang,Samsung Electro-Mechanics, Gyunngi-Do, Republic of Korea & 2009 Elsevier B.V.. Int
Trang 1Portable Devices: Fuel Cells
A Kundu,Queen’s RMC Fuel Cell Research Centre, Kingston, ON, Canada
JH Jang,Samsung Electro-Mechanics, Gyunngi-Do, Republic of Korea
& 2009 Elsevier B.V All rights reserved.
Introduction
The rapid growth of the portable electronics market
includes ‘power-hungry’ accessories in a smaller system,
which has led to the search for an alternative and
ad-vanced power source due to the limited energy density of
conventional lithium-ion batteries Table 1 lists the
power demand of the different portable applications
Fuel cells promise to provide a more reliable and longer
operational time than batteries As the energy is stored as
a reservoir rather than as an integral part of the power
source, fuel cells have advantages over batteries Micro
fuel cell products compete with power systems that
utilize both direct and indirect energy conversion
methods Direct conversion may involve fuels such as
methanol, ethanol, formic acid, ethylene glycol, and
so-dium borohydride that are converted into electrons
through a direct fuel cell system Indirect methods
re-quire the conversion of methanol, ethanol, or sodium
borohydride into hydrogen The direct supply of pure
hydrogen is relatively difficult in electronic equipment
applications due to storage problems (i.e., the lack of an
efficient hydrogen storage material) There is also
con-cern in terms of safety while carrying pure hydrogen in
electrical equipment The setup of a cost-effective,
ap-propriate infrastructure for distribution of hydrogen
canisters is another major challenge for which most
hurdles are unlikely to be overcome in the foreseeable
future In the direct alcohol fuel cell system, the main
studies center on methanol (direct methanol fuel cell
(DMFC)) although ethanol-fueled systems have drawn
interest in recent years Direct mathanol fuel cell has the
drawback of a high fuel crossover rate and a low rate of fuel oxidation
The micro fuel cell market can be divided into three device categories: portable electronics, military portable, and healthcare segments In the portable electronics category, this includes handsets, personal digital assis-tants (PDAs), mobile phones, portable audio/video de-vices, digital imaging dede-vices, and notebook computers Micro fuel cell technologies face competition from advanced energy storage devices such as secondary (chargeable) batteries, for example, lithium-ion batteries and nickel-based batteries However, micro fuel cells, once commercialized, hold the promise for providing more backup ‘green power’ at lower cost than competing battery technologies
It is most unlikely that micro fuel cells will compete with the primary battery In order to compete with the primary battery, the cost component would not justify the use of micro fuel cells Theoretically, competition with batteries from fuel cells impacts all sources of secondary batteries; however, practically it is only the high-cost, premium batteries (lithium-ion and lithium-polymer) that fuel cells really compete with Those products that can realistically use Ni–Cd or Ni–MH are not likely to support the cost premium required for fuel cells, at least not initially The added functions and features for more entertainment and sophisticated communications on modern handsets such as third-generation (3G) mobile phones, digital multimedia broadcasting phones, and iPhonesuse up available power very quickly Therefore, users are going to be faced with recharging their phones more often In this case, micro fuel cells have the po-tential to improve the user’s situation In addition, the price of 3G handsets is high enough to absorb the higher cost of embedded fuel cells Micro fuel cells will have to compete with the rechargeable battery not only in terms
of cost but also in terms of the run time, lifetime, and output power level Apart from mobile phones, another potential market for micro fuel cells is in notebook computers The potentially longer run time of a micro fuel cell may be competitive with conventional batteries for the notebook computer In addition to individual portable consumer electronic products, the other po-tential market for micro fuel cells is as battery chargers
As the battery chargers are not integrated with the de-vices, these are much simpler to develop and market There is great opportunity for micro fuel cells in the military market where there is an aggressive requirement
Table 1 The power demand of the different portable
applications
(W)
Personal digital assistant (PDA) 1
Notebook personal computer 20–30
Playstation portable (PSP) 2
Digital multimedia broadcast-receiving
(DMB) phone
3
39